Cooling systems or air-conditioning units for motor vehicles typically comprise a compressor, an expansion valve, an evaporator, and a condenser. Within the air-conditioning unit there circulates a coolant which can be, in particular, carbon dioxide (CO2). CO2 is also designated as refrigerant R744. Within the air-conditioning unit, the CO2 can be compressed by the compressor. Here, the compressor is typically driven by means of a belt drive which in turn is driven by an internal combustion engine of the motor vehicle. In the case of known motor vehicles, in particular hybrid vehicles, there is an engine stop function employed in order to reduce the fuel consumption of the motor vehicle.
However, the compressor of the air-conditioning unit is, as described above, usually coupled to the belt drive, and therefore the internal combustion engine must run in order to operate the air-conditioning unit. Although there is always present within the air-conditioning unit a certain latent cold, in particular in a mass of a heat exchanger or evaporator of the air-conditioning unit and of the refrigerant, this latent cold is as a rule already consumed after a few seconds and is no longer available for the cooling in particular of an interior of the motor vehicle. In order further to allow a further cooling of the interior and consequently a travel comfort for passengers of the motor vehicle, the internal combustion engine is as a rule started again, thus making it more difficult to save fuel.
Also known are extinguishing systems for motor vehicles, which comprise CO2 as the extinguishing agent. CO2 is particularly suitable for extinguishing smoldering fires of electronic components, liquid fires of crude oil derivatives and solids fires triggered by crude oil derivatives.